“My little children, for whom I labor in birth again until Christ is formed in you” (Galatians 4:19).
While a baby has all of its parts formed at birth, those parts are not fully developed—that comes with time and growth. So it is with becoming a child of God. Spiritual birth is only the beginning of the process of becoming a full-grown Christian. Evidently, this growth had not yet taken place with the Galatians
That’s the analogy the Apostle Paul uses in this letter to the Galatians as he writes to help them deal with the problem of Judaizing teachers and teaches them about growth as a child of God. His deep concern for them will remain until Christ is formed in them and they grow spiritually.
For Christ to be formed in us, we must truly invite Him into our hearts and minds so that He influences not only our thinking but also our actions. We must grow to the point that we get over being self-righteous and we rely on Christ, on His instruction, and on His righteousness for our spiritual condition. He must become the center of our lives if He is truly formed in us.